This invention relates to apparatus for filtering cigarette smoke and it relates in particular to cigarette holders that incorporate a filtering element. While the invention is not limited thereto, it is particularly useful for incorporation in a "smoker's withdrawal kit" of the kind which includes several cigarette holders arranged to admit ambient air to dilute the smoke in different degrees.
One of the more successful methods for enabling smokers to withdraw from the habit of smoking cigarettes involves removing portions of the habit forming nicotine compounds from the smoke. A gradually increasing proportion of those materials is removed and many of the smokers who can make themselves follow such a withdrawal program find that they are able to discontinue smoking. The habit forming materials can be condensed out of the smoke and removed in a filter along with various tarry and liquid materials that can be harmful if inhaled.
It is a feature of that method that the smoker continues to smoke until a time near the end of the process when the proportion of habit forming material is so small that the urge to smoke is slight and quitting is easy. The proportion of nicotine product that is inhaled is reduced by adding ambient air in parallel with the smoke so that the volume of smoke that reaches the smoker's lungs is reduced. While the cigarette is consumed somewhat less rapidly when inhalation suction results in the introduction of ambient air that need not travel through the cigatette, most of the cigarette is consumed between "puffs," and the net effect is that less smoke reaches the user's lungs.
In another method, the proportion of harmful ingredients that reaches the smoker's lungs is reduced, not by introducing fresh ambient air with the smoke, but by increasing the effectiveness of the filtering action. That latter method is costly to accommodate because the filters that are employed near the end of the withdrawal program must be much more effective than the filters that are employed early in the process. As a consequence, different filter designs are required and much more expensive tooling is required. Moreover, effective filters become loaded with solids and semi-solid materials and lose their effectiveness so that they have to be changed frequently. For whatever reason, experience has demonstrated that the filters are not changed with the required frequency to the end that the method is rendered ineffectual. While filters that do not load rapidly can be made, they tend to be expensive, and to occupy an unduly large amount of space.
Some of the more successful smoker's withdrawal apparatus combines the method of admitting ambient air to the smoke stream with the method of increasing the effectiveness of the filtering action. In that combined method it is possible to utilize ambient air in accomplishing the filtering action. Ambient air is cooler than the smoke and it can be used to aid in accomplishing condensation of the solid and semi-solid materials that are customarily called "tars and nicotine."
A number of devices that employ that combined method have been created. The method is conveniently practiced by adding an air inlet opening and a filter to an otherwise conventional cigarette holder. A number of withdrawal kits have been based on that general structural arrangement.
To practice the modified method, it is necessary to have available an apparatus which accomplishes the filtering action and which admits ambient air, and which by alteration of the filtering action or the quantity of air admitted, results in delivery to the smoker of a gas which contains a proportion of tar and nicotine that diminishes with time. That can be accomplished by changing the filter element or by changing the air inlet opening, or both. To change the size of the air inlet opening has been more convenient, and it is the arrangement most often adopted by patentees and producers of smoker's withdrawal apparatus.
Not all who use smoker's withdrawal kits attempt to withdraw entirely from smoking. A large portion of users utilize the withdrawal kit apparatus to limit their intake of tars and nicotine without reduction in their use of cigarettes. The objective of such a user is better served by providing him with an apparatus whose filter element can be cleaned and need not be replaced.